This application claims priority to an application entitled xe2x80x9cREGULATOR SYSTEM FOR CONTROLLING OUTPUT VOLTAGE AND METHOD OF CONTROLLING THE SAMExe2x80x9d, filed in the Korean Industrial Property Office on Aug. 9, 2001 and assigned Serial No. 2001-48062, the contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates generally to a regulator system, and more particularly to a regulator system and method for controlling an enable period of an input signal to control an output voltage.
2. Description of the Related Art
Generally, a regulator, for example, a low drop output (LDO)-type regulator, is adapted to convert the level of an input signal into a predetermined value and output the resulting signal. A general structure and output voltage of such a regulator will hereinafter be described with reference to FIGS. 1 and 2, respectively.
FIG. 1 illustrates the structure of a general regulator. As illustrated in FIG. 1, the regulator has four terminals, an input terminal INPUT for receiving an input signal, an enable terminal ENABLE for receiving an enable signal to drive the regulator, an output terminal OUTPUT for providing an output signal based on the input signal in response to an enabled state of the regulator, and a ground terminal GND. Upon receiving the enable signal, the regulator converts the level of the input signal received through the input terminal into a predetermined value and provides the resulting output signal through the output terminal. The relationship between the input signal to the regulator and the output signal from the regulator will hereinafter be described with reference to FIG. 2.
FIG. 2 is a timing diagram illustrating an input/output signal relationship of the regulator of FIG. 1. In FIG. 2, the reference character (a) denotes the enable signal and (b) denotes the output signal. If the enable signal (a) is turned on, then the signal (b) is outputted after a predetermined time delay. If the enable signal (a) is turned off, then the output of the signal (b) is stopped similarly after the predetermined time delay. Namely, the enable signal (a) acts to turn on or off the output of the regulator, or the output signal (b). The period in which the enable signal (a) remains ON will hereinafter be referred to as an xe2x80x9cenable active periodxe2x80x9d. When the regulator is a high active device, it is enabled to output the signal (b) when the enable signal (a) is high, and it is disabled to stop the output of the signal (b) when the enable signal (a) is low. On the contrary, when the regulator is a low active device, it is enabled to output the signal (b) when the enable signal (a) is low, and it is disabled to stop the output of the signal (b) when the enable signal (a) is high. Here, the output signal (b) has a voltage level as indicated by Vout.
However, the above-mentioned regulator has a disadvantage in that the voltage level Vout of the output signal (b) cannot be changed because it is preset in a manufacturing process of the regulator, thereby making it impossible for the regulator to output a signal of a different voltage level as may be desired by a system.
Therefore, the present invention has been made in view of the above problem, and it is an object of the present invention to provide a regulator system and method for controlling an enable period of a regulator to control the level of an output signal.
In accordance with one aspect of the present invention, the above and other objects can be accomplished by utilizing a regulator system for controlling an output voltage, comprising a regulator, enabled in response to an enable signal, for converting a level of an input signal into a predetermined value and providing the resulting first output signal; a smoother for smoothing the first output signal from the regulator and providing the smoothed signal as a second output signal; and an enable signal generator for generating an initial version of the enable signal to control an enable period of the regulator in such a way that the second output signal has a target level and adjusting an enable active period of the initial version of the enable signal to generate a new version of the enable signal when a level of the second output signal associated with the initial version of the enable signal is different from the target level.
In accordance with another aspect of the present invention, there is provided a method for controlling a regulator system controlling an output voltage, the regulator system including a regulator, enabled in response to an enable signal, for converting a level of an input signal into a predetermined value and providing the resulting first output signal, and a smoother for smoothing the first output signal from the regulator and providing the smoothed signal as a second output signal, the method comprising the steps of: a) generating an initial version of the enable signal to control an enable period of the regulator in such a way that the second output signal has a target level; b) checking a feedback level of the second output signal associated with the initial version of the enable signal; and c), if the feedback level of the second output signal associated with the initial version of the enable signal is different from the target level, adjusting an enable active period of the initial version of the enable signal to generate a new version of the enable signal.